Digital Frequency

Measurement

Teledyne Defence & Space’s Instantaneous Frequency Measurement (IFM) module, also known as a Digital Frequency Discriminator (DFD), offers high speed frequency measurement across the full operating bandwidth.

The IFM measures the frequency of RF signal present at its input and presents a result at its output as digital data. The RF input signal is conditioned by an RF amplifier that provides sufficient drive for the frequency resolving circuits. The raw video from the resolvers is digitised and processed into the required output format. There is additional timing and control circuitry which initiates the measurement process and provides handshake data to the host system processor.

The Digital IFM uses digitally implemented phase correlation where the correlators are realised in FPGA using a patented technique developed by TDS. The TDS standard provides a 12-bit digital output representing the frequency of an RF signal, in the range 0.5GHz to 2.4GHz, at its input. It is a clocked sampling DIFM (samples the RF input on the rising edge of every master clock cycle and provides a digital output accordingly). Alternatively, a mode is available where the frequency measurement word is updated in response to an external trigger input signal. The digital IFM offers a more compact solution in terms of size, weight and power (SWaP) consumption when compared with a more conventional analogue IFM operating at between 500MHz and 2.4GHz. The DIFM has been extended up in frequency and now offers a 2 to 6GHz variant in addition to the standard module.
​